9:00 AM - 9:15 AM
[G04-3-03] Loading effects caused by storm surges in the Rio de La Plata / Argentina: A model proof by a high resolution gravity time series
In December 2015, the Superconducting Gravimeter SG038 was put into operation at the Argentine – German Geodetic Observatory (AGGO) located near the city of La Plata, Argentina. Since then, gravity variations are continuously recorded with highest precision and temporal resolution.
By careful preprocessing of the gravity time series of the first year applying a remove-restore procedure, spikes and high frequency disturbances and one step caused by a power failure were corrected. The series was then filtered and downsampled to hourly resolution and atmospheric effects were removed using numerical weather models. Now a detailed Earth tide analysis was performed separating more than 50 wave groups and a treating degree three tide generating potential independently by making use of the capabilities of the latest version V60 of the Eterna software package. Despite these efforts, the residual gravity time series still shows significant non-tidal variations reaching up to several microGal which could not be explained by the applied models but are correlated with extreme weather events.
Wind effects are causing surges at the Rio de La Plata during these events. By using tide gauge observations around the river and a simple empirical astronomical tide model (SEAT) it was possible to compute the propagation of the storm surges landwards from the estuary. The resulting loading effect in terms of gravity shows excellent agreement with the residual gravity time series. This proofs both, the high quality of the gravity time series and the validity of the storm surge model, which allows to isolate gravity effects due to local water storage changes in the gravity record. Perspectively, this model can be used to correct these loading effects also in terms of position changes, which becomes essential as a correction of the results from space geodetic techniques (GNSS, SLR, VLBI) currently established at the observatory.
By careful preprocessing of the gravity time series of the first year applying a remove-restore procedure, spikes and high frequency disturbances and one step caused by a power failure were corrected. The series was then filtered and downsampled to hourly resolution and atmospheric effects were removed using numerical weather models. Now a detailed Earth tide analysis was performed separating more than 50 wave groups and a treating degree three tide generating potential independently by making use of the capabilities of the latest version V60 of the Eterna software package. Despite these efforts, the residual gravity time series still shows significant non-tidal variations reaching up to several microGal which could not be explained by the applied models but are correlated with extreme weather events.
Wind effects are causing surges at the Rio de La Plata during these events. By using tide gauge observations around the river and a simple empirical astronomical tide model (SEAT) it was possible to compute the propagation of the storm surges landwards from the estuary. The resulting loading effect in terms of gravity shows excellent agreement with the residual gravity time series. This proofs both, the high quality of the gravity time series and the validity of the storm surge model, which allows to isolate gravity effects due to local water storage changes in the gravity record. Perspectively, this model can be used to correct these loading effects also in terms of position changes, which becomes essential as a correction of the results from space geodetic techniques (GNSS, SLR, VLBI) currently established at the observatory.